Fix Trac #3590: a nasty type-checker bug in left/right sections
authorsimonpj@microsoft.com <unknown>
Tue, 20 Oct 2009 15:55:40 +0000 (15:55 +0000)
committersimonpj@microsoft.com <unknown>
Tue, 20 Oct 2009 15:55:40 +0000 (15:55 +0000)
commit0cffd31b0f25c2a31ed6eff2c0c0b1b1a8a8d507
treecabf8dbe415d9b19cb97c46050d196355a6f4677
parent8277f2dcff54748269c204c31b15f9ea55f9b6e2
Fix Trac #3590: a nasty type-checker bug in left/right sections

The bug related to the fact that boxyUnify (now) returns a coercion,
which was simply being ignored.  (TcExpr is clearly not warning-free
wrt the unused-monadic-bind thing!)

Anyway, it's fine now.  I added a test case to the test suite.

MERGE to 6.12 please.
compiler/typecheck/TcExpr.lhs